|Perry and Mayer at the Grammy Awards|
While the long-term friends have recently been romantically linked after growing close in the wake of the 'Twilight' actor's split from Kristen Stewart, Katy confessed this week she is still "madly in love" with her ex-lover John Mayer.
Her friends hope she chooses to make Rob - who recently spent a week at her house - her man because he would be a steadying influence on the pop superstar and is a great guy.
One pal told America's OK! magazine: "My vote is for Rob.
John is a bad boy and sadly Katy prefers that. She always falls for guys with an edge. With that edge comes drama and John is the king of drama."
However, Katy's inner circle believe she will give John another chance because she is so physically attracted to him.
The source added: "John is a physical guy and Katy says it has been the best sex of her life."
The 'Part of Me' singer - who was previously married to Russell Brand - revealed her romance with John, who has a reputation as a womanizer, is definitely over but admitted she still had deep feelings for him.
She revealed: "It's over ... I was madly in love with him. I still am madly in love with him. All I can say about that relationship is that he's got a beautiful mind. Beautiful mind, tortured soul. I do have to figure out why I am attracted to these broken birds."